84 D100 318 with spd+OD manual gearbox
equipped with original equipment carb
was running fine until today; it starts and idles fine but if you goose it, there is a big flat spot
it hesitates and has a slight miss at cruising speed and is sluggish on acceleration
I suspect the fuel pump is on its way out and the beast is simply bot getting enough gas
a fuel pump is cheap and i will throw one at it
but does anyone think I am on the wrong track here
charlie1935
04-05-2007, 07:14 PM
While you have the fuel pump off stick a finger in the hole where it mounts and check for play in the timing chain. I'll bet its loose as a goose. :gr_patrio
bherder
04-05-2007, 09:55 PM
I think I'd also be looking at ignition also....
I had much the same problem that happened 'overnight' and after spending a lot of $$ on other stuff, it turned out to be bad plug wires....
And not to say Charlie is wrong, because it could very well be chain and gears, I've only ever had that prob once on a 340 Duster I used to own...
Timing chain jumped a tooth one day (and it turned out to be only ONE tooth) but I could barely even get it started, let alone running like it should...
(After that, double-rollers on everything... Don't leave home without it! :D )
You also might want to be looking at the accelerator pump... Check and see if your getting a nice healthy squirt of gas...
charlie1935
04-05-2007, 10:33 PM
I didn't mean to imply that the timing chain was causing his problem, but if it is original it's for sure worn out. Even if it has been replaced with OEM parts and has just a few thousand miles it's most likely junk. I agree with the double roller set, only way to go. :gr_patrio
sgillett
04-05-2007, 10:39 PM
Don't forget the fuel filter!
Scott
Dodgevanman
04-06-2007, 07:15 AM
One thing to consider is a severely worn fuel pump eccentric. This is the piece that drives the fuel pump rod. Over the course of many years, they get grooved and then your fuel pump doesn't pump efficiently.
acton mike
04-06-2007, 02:06 PM
presumably the eccentric that drive the fuel pump is on the cam and this would mean replacing the cam
If that be the case, is there an electric fuel pump that I could install - I am really not up to swapping out a cam - too much on my plate already
I will look at the accelerator pump as soon as the weather warms a little - good grief - easter weekend with snow and minus 10 celsius degrees - bloody strange when i was out working on the truck in my shirt sleeves on January 2
Oh well; winter started late so I guess it will end late
Back to the accelerator pump i had the carb rebuilt about 18 months ago and I do not think I have put 2500 miles on the beast
I will check the timing chain when I do the pump and I will check the eccentric at the same time
I have no doubt that the timing chain may past its sell-by date; the truck was 21 years old when I bought it; the speedo only reads reads to 99,000 kilometers and then it it starts again at zero; it read about 14,000 when I got it and so it could have a couple of hundred thousand klicks on it
A timing chain looks like a good project for the long week-end in may
Speed Dragon
04-06-2007, 04:41 PM
No no, the eccentric bolts to the front off the cam, it's not part of the cam. Just have to pull the timing cover to get it.
bherder
04-07-2007, 08:58 AM
No no, the eccentric bolts to the front off the cam, it's not part of the cam. Just have to pull the timing cover to get it.
Yes! There you go....
The eccentric (As Speed says) on a small block bolts to the front of the cam, in front of the gear. It's basically a kind of freeze-plug shaped thing that is drilled off-center, so when it spins around, it pushes on the arm of the fuel pump (No rod involved) and... pumps.
Don't worry about pulling the cam!....
I've never (Unless it was a severe case of oil starvation) seen one go bad. Then again, I haven't seen everything ;)
I can tell you, they don't (If ever) go bad overnight....
If you're wondering about the fuel pump, just undo the fuel line at the carb and hold a mason jar to catch the gas. Have someone crank the engine. It'll run for a minute, but you'll know PDQ if the pump is 'putting out' or not... you should be getting a nice healthy squirt of gas, not a dribble or drool....
farmguy
04-07-2007, 09:47 PM
I`ll second that emotion for the double roller timing chain set.......One little trick, is to soak that new chain in 30W. motor oil for about 1/2 hr before installing. Putting a dry chain on and crankin her up, will cause a little pre-mature wear till she gets oiled up good.
acton mike
04-08-2007, 10:30 AM
I was only going to consider changing the camshaft if the fuel pump drive eccentric was an integral part of the cam
But I gather that is is a separate piece that is fastened to the cam with screws or bolts or the like
Is it a part that I can buy at CarQuest/whatever parts store you care to name or is the counter guy going to look at me as if I have two heads when I ask him for the piece
Speed Dragon
04-08-2007, 10:35 AM
Parts stores may have it, if not, dealer or junkyard.
acton mike
04-08-2007, 10:40 AM
If I have the timing cover off, I might as well put a timing chain in if it shows any signs of wear
One must be wary of the might-as-well syndrome; it has a habit of making the bills at the part store get out of hand
The advice about double roller chain is probably good advice
However, I put very little mileage on the truck - maybe 50 miles a week and so it might not be worth the extra dollars
I have been reading my Haynes books and finding out what is involved in changing the timing chain. It makes comment that the oil pan might have to come off to do the job is there any truth to this
bherder
04-08-2007, 10:59 PM
If I have the timing cover off, I might as well put a timing chain in if it shows any signs of wear
One must be wary of the might-as-well syndrome; it has a habit of making the bills at the part store get out of hand
The advice about double roller chain is probably good advice
However, I put very little mileage on the truck - maybe 50 miles a week and so it might not be worth the extra dollars
I have been reading my Haynes books and finding out what is involved in changing the timing chain. It makes comment that the oil pan might have to come off to do the job is there any truth to this
If this is a very little used (As you say, 50 miles a week) rig, I might go with a 'stock' set of timing chain/gears... just for 'costs' sake... You can get a whole new set of everything for about $30-40.00 ....
NO, you do NOT have to pull the pan to change out the timing cover... If you buy a 'timing cover set' gasket kit, it will have the 'end pieces' and rubber gasket you'll need to replace the timing cover....
Keep in mind, it's a bit of a pain to scrape/clean and remove all the old gasket you'll need to do, to make sure the new stuff seals and lines up correctly...
(Here's a hint... Been here and done that ;) )
After you've got everything cleaned and scraped and are ready to put the timing cover back on.. Even though they are the worst bolts to get to, get the bottom ones (Up through the oil pan to the bottom of the timing cover) in FIRST and get them 'sorta' cinched up. Sorta' tight, but leave a little bit of wiggle to them... If you don't, none of the other bolt holes will line up.... Make sure you have ALL the bolts 'started' before you tighten them up...
And yes, you'll have to wiggle & jiggle things around a bit to get all the bolts started.. After you do, though.... It's GRAVEY afterwards! :D
Oh, another thing... The seal for the crank in the timing cover? Pretty easy to get the old one out, but getting the new one in, is a bit of a pain... Very close fit, so, unless you have a fancy-dancy seal-installing tool, you're going to have to dance very gently with a light hammer all around edge to get it in straight and then get it fully seated....
